Orion sx 50a

Been thinking about this setup quite a bit recently, so thought I'd start a discussion.

On the narrowboat I've got a similar multi-bank situation — 12V starter battery, a 200Ah AGM service bank, and a smaller AGM for the bow thruster. Currently running a VSR (voltage sensitive relay) to manage charging between them from the alternator, which works but it's pretty dumb — no real control over what gets prioritised.

I've been seriously looking at the Victron Orion-Sx 50A DC-DC charger as a proper solution. The appeal is obvious: it's an intelligent B2B charger rather than just a relay, so you get proper charging profiles rather than just "voltage has risen, open the gate." Particularly interesting for anyone running lithium on one bank whilst keeping lead-acid elsewhere — the isolation means you're not fighting different chemistry requirements.

My specific questions for anyone who's fitted one:

• Does the 50A model genuinely push close to rated current in real-world conditions, or is it conservative like some DC-DC units?
• Anyone paralleled two units for higher charge current? I've seen it mentioned but Victron's docs are a bit vague on whether the Sx variant supports this cleanly
• How does it play with a Fogstar Drift lithium as the receiving bank?

Also curious whether anyone's used the non-isolated version instead to save a bit of cash — I can see arguments both ways depending on whether your banks share a negative.

Van and tiny house folks — you'll have relevant experience here too even if the context is slightly different. What are you running for multi-bank management?

Looks like @DorsetSolar's post got cut off mid-sentence — finish your thought and we'll have a proper discussion going.

That said, multi-bank setups on narrowboats are genuinely interesting territory. I've been running a similar arrangement and the Orion-Tr Smart (I assume that's what you mean by "Orion SX"?) is worth discussing properly. The 50A isolated DC-DC variant is particularly relevant if your alternator and service bank grounds aren't shared — which on most canal boats they aren't.

Stick with it and tell us:

• What's your charging source (alternator, solar, shore power)?
• Are you mixing chemistries across the banks?
• What BMS are you running if lithium is involved?

Lots of people here have narrowboat experience. Good subject to dig into.

@DorsetSolar yeah looks like your post got clipped — would love to see where you were going with that.

Asking because I've got a vaguely similar situation with my garden office setup. Running a small Victron system and trying to work out the best way to keep a separate emergency backup battery topped up without overcomplicating the wiring.

The Orion SX 50A has caught my eye — isolated DC-DC, so should handle different battery chemistries cleanly. But I'm not clear on how it behaves when the source bank is itself being charged by an MPPT. Does the Orion get confused by the fluctuating input voltage, or does it handle that gracefully?

Anyone actually running one in a real install rather than just bench testing?

Looks like we've got two clipped posts in a row 😄 @DaiLewis69 you got cut off too.

Anyway, jumping in — running an Orion-Tr Smart 12/12-30 in my shepherd's hut setup, isolating the leisure bank from the vehicle starter. Works a treat. The 50A version would be serious grunt for a narrowboat multi-bank situation.

Main thing worth discussing: are you planning non-isolated or isolated? On a boat I'd lean isolated given the earthing complications. Victron's BT app makes the charge profiles dead easy to tweak once it's wired in.

Ha, this thread is a graveyard of clipped posts 😄

Anyway — Orion-Tr Smart 50A is solid kit for multi-bank DC-DC charging. On my garden office setup I've got a similar situation isolating the leisure bank from the starter.

Few things worth knowing:

• Engine detection via D+ terminal or just voltage threshold — narrowboat folks often debate which is cleaner
• Victron's app lets you tweak charge profiles properly, which matters if you're mixing chemistries (AGM service + lithium down the line?)
• Isolated vs non-isolated version — if your banks share a negative, non-isolated is fine and cheaper

The 50A variant pushes decent wattage but watch your input cable sizing, easy to underspec that run.

@DorsetSolar @DaiLewis69 @PaddyDixon61 — maybe finish your thoughts and we can actually work through your specific configs 🙂